1. The Field of the Invention
The present invention relates generally to analog circuitry. More specifically, the present application relates to circuitry and methods for performing ambient light suppression in a photodiode receiver application.
2. Background and Relevant Art
Optical systems are used for a wide-variety of applications in order to communicate information and detect environmental conditions. Optical systems typically include a transmitter that sends out a modulated optical signal, and a receiver that may receive at least a distorted version of the modulated optical signal.
In one application, optical system may be used to detect the presence of an object in a given volume. The transmitter transmits the modulated optical signal into the given volume. If an object is present in the volume, a portion of the optical signal is reflected back into the receiver. The receiver may thus detect, based on the reflected light, whether there is an object in the volume. Conventional obstacle detection mechanisms often employ this technology. If an obstacle is introduced into the path of the optical signal, an attenuate form of the signal is reflected to a photodiode receiver. The receiver then processes the received signal allowing the system to detect the obstacle and effect some appropriate control.
As previously mentioned, optical systems are used to detect the presence of an object in a given volume. In many cases, the volume under examination is not only subject to the modulated optical signal, but is also exposed to ambient light optical signals. The ambient light optical signals include Direct Current (DC) components. In addition, the ambient light optical signals also include relatively low frequency components compared to the higher frequencies of the modulated optical signal. The ambient light optical signals received by the photodiode receiver can cause a false positive detection of an object within the volume, thereby frustrating the purpose of the object detection mechanism.
Therefore, what would be advantageous are photodiode receiver circuits that effectively suppress ambient light while allowing higher frequency modulated optical signals to be detected.